Welcome to the OpenJDK BSD Port wiki.
Installing
Some operating systems include packages of the BSD port. Some of them use OpenJDK 7, others use a backport of the BSD port to OpenJDK 6.
OpenJDK 6
FreeBSD
There is an OpenJDK 6 package in the FreeBSD Ports collection called openjdk6.
Darwin/Mac OS X
There is an OpenJDK 6 package in MacPorts called openjdk6. To install it, after installing MacPorts, use sudo port install openjdk6 in the Terminal application.
If you do not see the openjdk6 port, try sudo port sync.
OpenJDK 7
FreeBSD
There is an OpenJDK 7 package in the FreeBSD Ports collection called openjdk7.
NetBSD
There is an OpenJDK 7 package in the pkgsrc package collection for NetBSD/i386 and NetBSD/amd64
called openjdk7.
DragonFly BSD
The pkgsrc openjdk7 package is also available for the DragonFly BSD i386 arch.
OpenBSD
There is an OpenJDK 7 package in the OpenBSD packages collection called jdk1.7.
Mac OS X
There may be no way to get pre-built binaries for installation of OpenJDK on Mac OS X.
Building from source
Mac OS X
Mac OS X 10.5 and Mac OS X 10.6, could be adapted from http://www.javarants.com/2009/11/01/building-openjdk-1-7-0-for-mac-os-x-10-6-snow-leopard/)
Switching Current JDK
Instructions for switching the current version of java visible to the OS on OpenBSD, NetBSD, and Mac OS X.